Triumphunittwinrebuild
With bits queued up and awaiting attention at specialist places, focus is on bits which have been ignored for a while.
There comes a time in any build project when there is no point trying to pretend that if you had ‘this bit of kit’ or the latest gizmo you could hurry things along. It’s the point when specialist attention really is needed.
Had I filled my workshop with fancy kit there is a good chance it would have gathered dust, as I’d still have to carry stuff to more competent machinists. However, there are a few bits of machinery I’ve collected over the years which I’ve used on my own motorcycles.
A drill press was the first acquisition, and given the nature of my family and the area I’m from, this drill press wasn’t new but was quite a robust and probably a professional or college thing. Unfortunately, I have no idea what make it is or what the spec may be. Why? It was rescued by a parent for whom the concept of leaving the maker’s ID labels on was totally alien... along with modern on/off switches, guards and other useful safety devices. What I DO know is the accuracy of drilled holes improves no end with such a machine.
It was superseded by a small, bench mounted drill which has gone above and beyond the call of duty in the years I’ve had it.
A later, much later, addition to the kit was a small lathe, a Hobbymat, which may not be the most exciting lathe in the world, but is almost perfect for me and may well be up to the task of accurately machining a nut to go on the end of an exhaust cam to carry the trigger for an electronic ignition… .
It may be up to that task, but I’m probably not, which is why the engine is in the queue at Audit CNC Ltd awaiting accurate machining… also there are the bits of oil tank awaiting welding, which means attention can go to other bits hitherto neglected.
Assembling a pile of bits collected over a number of years and not always from the same manufacturer is always going to be interesting. The big bits do often go together relatively easily but, as ever, it is the myriad smaller details where the bit from make ‘A’ joins components from make ‘B’ so parts from make ‘C’ can line up and so on. One bit which has caused some head scratching has been the steering stops – you know, the bits which prevent the forks from turning too far and denting the petrol tank. On some bikes, a simple bit of bar welded to the frame does the job, on others an Allen bolt is screwed into a tapped hole. Some unit Triumphs use
an extended nut on the clamp bolt on the bottom yoke which butts against the frame tube as the fork is turned. I’ve never been a big fan of this method, the nuts bend too easily and as I’m using BSA yokes – because I want 1⅜in diameter stanchions rather than Triumph’s 1¼in ones and the Triumph yokes don’t have enough meat on them to bore out – there are other options. The Allen bolt stop idea as used on my B40 was discarded as there’s not a hole in the headstock casting to take it. Almost since the outset this problem has been niggling away, a few ideas came and went, including one which might be revisited eventually.
When Triumph re-worked its Adventurer model into something more ISDT suitable, the work included adding Betor forks to the Triumph frame. The solution to the steering stop problem was simple and possible because of the way Betor yokes are made. An alloy plate, shaped to form a stop, was bolted to the yoke and the lugs butt against the frame. With glee I sketched out a similar idea and the two brackets needed to hold in in place, plus the hole for the front bolt. Then the clamp bolt holes needed drilling out as on BSAs they are tapped… and so on. All of a sudden the elegant simplicity was replaced by something incredibly complicated. Back to the sketch pad…
Some readers may recall the UK comedian Tommy Cooper whose act included a magic trick where he would attempt some basic conjuring and tease the audience with a short commentary on what was going to happen. This commentary was along the lines of ‘ball, jug… jug, ball…’ as Tommy held up each bit he was describing.
I found myself doing a similar thing as I looked at the fork yokes and the frame, ‘yoke, frame... frame, yoke’ I kept repeating. Then noticed the lug, for the Triumph steering damper anchor plate to bolt on to, cast into the head stock of the frame. A 10mm bolt slid through this lug, a couple of pieces of alloy plate shaped to fit and held in place by the bolt and it seemed to do the job.
There was nothing fancy about making the bits – a file and drill were all I used. There was some thought that perhaps the lug might break, but if I got into such a tankslapper then a broken lug would be way down the list of things to worry about. All in all though, I rather wish I’d done this a while ago, as the nice throttle cable I made slipped down under the frame stay and the bottom yoke nipped it and crushed the outer wire, so a new cable is needed.
Thinking more about the yokes, I’m not 100% convinced they look right and may well investigate further – had there been autojumbles I’d likely have picked up a C15/B40 set which are slimmer than the B25 type I did have in a box under the bench – I think they came with the B40 years ago – though another option is to have a new bottom yoke made which matches the Triumph competition top yoke, or ‘lug’ as Triumph described them. Both ideas have a lot of merit and which one I go for is yet undecided… I do want to keep the appearance of the bike as 1960s, yet want it to work too.
Meanwhile, as I ponder such things, there’s the clutch… three-spring, four-spring, with the baskets having a number of depths too. What I do know is the whole primary drive is quite heavy, and works team members such as Roy Peplow had whole drives made from as much alloy as possible.